This combination of file pictures shows candidates for the upcoming UN secretary-general election (from top left) former UN high commissioner for refugees Antonio Guterres, United Nations Development Programme (UNDP) head Helen Clark, Montenegro's deputy prime minister Igor Luksic, director-general of UNESCO Irina Bokova, former minister of foreign affairs and European integration of Moldova Natalia Gherman, former president of Slovenia Danilo Turk, former Croatian foreign minister Vesna Pusic, and former prime minister of Macedonia and former UN General Assembly president Srgjan Kerim, created on April 12, 2016. (Photo/Xinhua)
